Method of orienting filaments in incandescent lamps



Jan. 3, 1967 A. J. HOLLENBECK 3,295,909

METHOD OF ORIENTING FILAMENTS IN INCANDESCENT LAMPS Filed Deo. 2v, 1965 FIG-Z.

VOLT/46E AMPLIFIER O c VOLTAGE -d United States Patent O 3,295,909 METHOD OF ORIENTING FILAMENTS IN INCANDESCENT LAMPS Arthur J. Hollenbeck, West Orange, NJ., assigner to Westinghouse Electric Corporation, Pittsburgh, Pa., a

corporation of Pennsylvania Filed Dec. 27, 1965, Ser. No. 516,651 8 Claims. (Cl. 316-23) This application is a continuation-impart of application Serial No. 403,810, filed October 14, 1964, for la Method of Orienting Filaments in Incandescent Lamps, and i-s owned by the same assignee as the original application.

This invention relates to a method of orienting filaments in an incandescent lamp and, more particularly, to method of orienting the filament in an incandescent lamp relative to a reference point on the outside of the lamp.

In some incandescent lamps, especially small incandescent lamps used in automobile indicators, it is required by yautomotive manufacturer specifications that the filament be oriented with respect to a reference pin on the base of the incandescent lamp. With a clear or transparent lamp bulb the filaments may be oriented optically by merely turning the lamp bulb in which the filament is mounted with respect to the reference point or pin on the base until the filament is properly oriented with respect to that reference point or reference pin. However, many colored `or translucent incandescent lamp bulbs are being used at present for indicators, or other purposes, wherein --because of the optical system used with the lamp it is necessary that the filament be properly oriented with respect to a reference point on the base of the lamp. This reference point is usually what is referred to in the art as the base or mounting pin, and is ka pin attached to the base which functions to hold the lamp in its socket. With colored or translucent incandescent lamp bulbs it is impossible to use an optical system for properly orienting the filament with respect to a reference point on the outside of the incandescent lamp.

The present invention provides a system wherein the filament after it has been mounted in the lamp bulb is excited with a very low A.C. voltage and the bulb is placed in the base of t-he lamp with the basing cement in place and a picloup means is placed adjacent the outside of the bulb, which pick-up means is responsive to the field generated by current flowing in the filament of the lamp. A voltage is generated in the pick-up means and this voltage is indicated on an A.C. voltmeter which is attached to the output of the pick-up means. The meter is calibrated to indicate the orientation of the filament with reference to a reference point on the outside of the lamp bulb. With this arrangement the yfilament can be rotated with respect to the reference point on the base of the lamp until any desired orientation of the filament is obtained, then the basing cement is cured and the leads from the filament are permanently attached to the end b-utton f the lamp and to the base.

It is also desirable to be able to automatically orient a filament within a bulb, and the field pick-:up method of the present invention is particularly adapted for such automatic filament orientation in either clear-glass or colored lamps. In su-ch automatic filament alignment, the output of the pick-up mechanism would be fed into a servo bulb-alignment device, thereby eliminating manualoptical focusing.

It is accordingly an object of this invention to provide an improved metho-d for accurately orienting the filament inside a lamp bulb with reference to a reference point external of the lamp bulb.

It is another object of this invention to provide an eleci trical method for accurately indicating the orientation of a filament inside a translucent or colored incandescent lamp bulb with respect to a .reference point externalof the lamp bulb.

It is a 4further object to provide an electrical method for accurately indicating the orientation of a filament inside an incandescent lamp bulb and then securing the bulb to the lamp base in a predetermined orientation.

These and other objects are effected by this invention as will be apparent from the following description taken in accordance with the accompanying drawings forming a part of this application, in which:

FIGURE 1 is a perspective view of an incandescent light bulb of the type to which this invention is applicable;

FIG. 2 is a cross-section of the lamp bulb of FIG. 1, taken along line II-II of FIG. 1, showing a color coating;

FIG. 3 illustrates how t-he filament of the lamp of FIGS. 1 and 2 i-s oriented on one position of a lamp basing machine;

FIG. 4 illustrates one position of the filament with respect to the reference point which results in maximum response on the indicator;

FIG. 5 illustrates another position of the filament with respect to the reference point with a resultant lack of response or null on the indicator;

FIG. 6 indicates a position of the filament with respect to the reference point and the pick-up device for a desired position somewhere between maximum and minimum response on t-h-e indicator; and,

FIG. 7 is a curve illustrating the relative field strength sensed by the pick-up device versus the angle between the filament axis and the axis Iof the pick-up device.

Throughout the description that follows, like reference characters refer to like parts on the various figures of the drawings.

In FIG. 1 there is shown a small incandescent l-amp 10, which is one of the many types of lamps to which this invention is applicable. The lamp 10 comprises a stem 12 which carries a pair of leads 14 and 16. A filament 18 is connected across the leads 14 and 16. The stern 12 is enclosed by a glass bulb 20. The neck of the glass bulb is sealed to a metallic 'base 22 by a suitable basing cement. The lead 14 is electrically connected to metallic base 22 and the lead 16 is electrically connected to metallic end button 24. A reference or mounting pin 26 is attached to the metallic base 22. In small incandescent lights, especially the type used for automobile turn signals, it is required that the filament 18 be oriented in a ldefinite position with respect to the base pin 26. This is required beca-use of special optical systems used with this type of lamp 4in the automobile industry.

FIG. 2 is a cross-section taken along the line II-.II of FIG. 1. FIG. 2 shows one orientation of the filament 18 with respect to the base pin 26. As shown in this figure the angle between an axis passing longitudinally through the 'base or mounting pin 26 and an axis passing vthrough the long direction of the filament 18 is approximately The usual installations require this orientation of the filament 18 with reference to the pin 26 and the present invention is particularly directed to accomplishing this result. However, it should be understood that the invention is capable of accurately determining any desired orientation without departing from the scope thereof. FIG. 2 also illustrates a color coating 28 which is required y011 some incandescent lamp bulbs of this type. However, this invention is not necessarily restricted to color coated lamps and it is emphasized that it could be applied equally as well to any incandescent lamp which requires a special orientation of the filament with respect to a reference point outside of the lamp bulb.

FIG. 3 illustrates how this invention is practiced at one stage on a conventional turret type lamp basing machine. At this stage on the machine, after the stem 12 carrying the filament 18 has been mounted in the bulb or envelope 20,-the base 22 is positioned in the base holder 30 and the 4chuck 32 moves up and holds the bulb 20 in the base 22. Then temporary electrical connections are made to leads 33 and 34 and a small electrical voltage is supplied to the filament 18 to cause a predetermined A.C. current to iiow. 'Ihese lamps are usually rated 6 to 12 volts. However, it is not necessary to apply the full voltage to the filament for this orientation. The voltage applied is usually somewherein the order of six tenths, or less, of a volt. This potential may be supplied from an alternating current source connected acro-ss the terminals 36 and the amount of the voltage applied is regulated by a variable rheostat 38. An electrical pick-up device 46 is placed adjacent the bulb 20. A voltage is induced in the winding of the pick-up device 46 due to theI field generated around the filament 18. The voltage pick-up from the field existing around the filament 18 may be in the order of a few millivolts and still provide a good signal for orientation of the filament. The output from the pick-up device 46 is applied to a voltage amplifier 40. The output from this amplifier 40 is connected to an indicating device or meter 42. The meter 42 is calibrated to indicate the angle of orientation of the filament 18 with respect to the mounting pin 26. The chuck 32 may be rotated by a shaft 44. In the orientation process, the chuck 32 is rotated and it in turn rotates the bulb 20 until an indication appear-s on the meter 42 that the filament is properly oriented with respect to the base pin 26. When the meter 42 indicates that the filament is properly oriented with respect to the base pin 26, rotation of the chuck is stopped, and the basing cement, which has been applied between t-he ibase 22 and the bulb 20, is cured to fasten the bulb 20 to the base 22 and thereby Ifasten the filament 18 in proper orientation with respect to the mounting pin 26. Then, the lead 34 is permanently soldered to the base 22 and the lead 33 is permanently soldered to the button 24` After this operation the lamp assembly is complete.

FIG. 4 illustrates one position of the filament 18 with respect to the mounting pin 26 and pick-up device 46. In the orientation shown, with filament 18 substantially parallel with the pick-up coil, an indication of maximum response will occur on the indicating device 42. As seen in FIGS. 4 and 5, the pick-up device 46 comprises a magnetic core 48 having an air gap therein, and having a plurality of turns of wire 50 therearound. The A.C. current flowing in the filament 18 sets up a field around the filament and this field links, by mutual inductance, with the turns 50 of the pick-up device of detector 46 and induces a voltage in the turns 50. The voltage induced in the turns 50 is proportional to the amount of the field generated around the filament 18 which is traversed by the turns 50. The amount of field strength which links with the turns 50 is determined by the position of the filament 18 relative to the turns 50, it being understood that the turns 50 have previously been oriented with rel spect to the base pin 26. When the filament is in the position indicated in FIG. 4, the pick-up device 46 is a maximum and a maximum response or indication will be indicated on the indicating device 42.

FIG. 5 illustrates the preferred position of the filament 18 with respect to the mounting pin 26 for automotive lamp purposes. In this position none of the turns 50 lie within the field generated by filament 18 and therefore a minimum response or null is indicated on the indicating device 42.

FIG. 6 illustrates an arrangement of the pick-up device 46 with respect to the filament 18 and base pin 26 which gives an indication on the indicating device 42 somewhere between maximum and minimum indication, This arrangement may be required where it is physically impossible to locate the pick-up device 46 at 90 to the pin 26.

It will be apparent that, after the instrument 42 has been properly calibrated, any desired orientation of the filament 18 with respect to the pin 26 may be obtained within the scope of the present invention.

It is understood that power may be supplied to the amplifier 40 from any conventional source.

FIG. 7 is a curve illustrating the relative field strength around filament 18 versus the degrees of rotation or angle between the axis of filament 18 and the X-X axis of pick-up device 46 shown in FIGS. 3 and 4. In the FIG. 4 position, the angle of rotation is 0 and the amount of coupling therefore a maximum with a corresponding maximum reading on meter 42. In the FIG. 5 position, the angle would be and therefore coupling a minimum and hence a null or minimum response on meter 42. In practice a 15 variance from 90 is acceptable and hence the steep sl-ope of the curve between 70 and 90 makes sensing for a null preferable because of the greater change in field strength per degree of angular displacement from a perpendicular relationship between the axis of the filament and the X-X axis of the pick-up device.

In the usual case, the filament 18 is required to be mounted so that it is generally perpendicular with respect to the axis of the bulb 20. Also, it is usually required that the filament 18 be disposed so that it is perpendicular to the base pin 26. If the filament were required to be aligned with the base pin 26, such a modified positioning could be accomplished by rotating the base holder 30 through 90 and continuing to tune for a null or minimum field signal. Of course, either a maximum or minimum signal may be used as the indicia of proper filament positioning but, as indicated supra, tuning for a null or minimum response is preferable.

In order to generate a field which varies in accordance with varying positionings of the filament, the filament,

should be elongated or otherwise nonsymmetrical. In addition, while the filament 18 is preferably perpendicular with respect to the axis of the bulb 20, the present method can be usedto orient a filament which is positioned within the bulb in almost any disposition.

It will be apparent that the coupling principle employed to induce a voltage in the pick-up coil 50 does not require that the pick-up device 46 be disposed ,laterally of lamp bulb 20 and that the device would operate equally well with the pick-up `device located above or below lamp bulb 20. Lamp bulb geometry and the present equipment employed to associate and seal a lamp bulb to its base make lateral disposition preferable.

From the above it is seen that with the method disclosed by this invention, after proper calibration of the apparatus, it is possible to accurately orient a filament inside a colored or translucent incandescent light bulb with respect to a reference point on the outside of the bulb. This cannot be done by optical means because of the color coating or the translucency of the light bulb. The present method is also applicable to automatic alignment or orientation of a filament in either a clear-glass or colored lamp.

While this invention has been described with reference to several embodiments, it is understood that modifications may be made therein Without departing from its scope.

I claim as my invention:

1. The method of orienting an elongated filament which is positioned within a sealed lamp bulb in a predetermined position with respe-ct to a reference point on the base of said bulb comprising the steps of:

(a) passing a predetermined current through said filament to generate an electric field therearound,

(b) measuring the relative intensity of the generated electric field at a predetermined location exterior to said bulb which location has a predetermined orientation with respect to said reference point on said lampbase,

(c) and rotating said bulb With respect to said reference point on said lamp base until the resulting relative magnitude of the measured electric field indicates that the filament is properly oriented with respect to said reference point on said base.

2. The method of orienting an elongated filament with respect to a reference point on the base of a lamp bulb according to claim 1 further comprising the step of securing the neck portion of said lamp bulb to said lamp base whereby -said filament is maintained in its properly oriented position with respect to said reference point on said base.

3. The method as specified in claim 1 wherein the resulting relative magnitude of the measured'electric field is a maximum.

4. The method as specified in claim 1 wherein the resulting relative magnitude of the measured electric field is a minimum.

5. The method of orienting a filament on the inside of an incandescent lamp bulb with respect to a reference point exterior to the lamp bulb compri-sing the steps of:

(a) exciting the filament of the lamp lbulb with a predetermined voltage,

(b) situating a pick-up device adjacent said lamp bulb in a predetermined position with respect t0 said reference point,

(c) measuring and indicating the relative intensity of the field generated about said filament by said predetermined voltage, and

(d) rotating said bulb with respect to said reference point until the measured relative intensity of said field is a predetermined quantity.

6. The method as specified in claim 5 wherein said predetermined quantity is the maximum intensity generated by said voltage at said location.

7. The method as specified in claim 5 wherein said predetermined quantity is the minimum intensity generated by said voltage at said location.

8. The method of orienting a filament as specified in claim 5 further comprising the step of securing the neck portion of said lamp bulb to said lamp base when said filament has been rotated to a predetermined position with respect to said reference point.

No references cited.

RICHARD H. EANES, .l R., Primary Examiner. 

1. THE METHOD OF ORIENTING AN ELONGATED FILAMENT WHICH IS POSITIONED WITHIN A SEALED LAMP BULB IN A PREDETERMINED POSITION WITH RESPECT TO A REFERENCE POINT ON THE BASE OF SAID BULB COMPRISING THE STEPS OF: (A) PASSING A PREDETERMINED CURRENT THROUGH SAID FILAMENT TO GENERATE AN ELECTRIC FIELD THEREAROUND, (B) MEASURING THE RELATIVE INTENSITY OF THE GENERATED ELECTRIC FIELD AT A PREDETERMINED LOCATION EXTERIOR TO SAID BULB WHICH LOCATION HAS A PREDETERMINED ORIENTATION WITH RESPECT TO SAID REFERENCE POINT OF SAID LAMP BASE. (C) AND ROTATING SAID BULB WITH RESPECT TO SAID REFERENCE POINT ON SAID LAMP BASE UNTIL THE RESULTING RELATIVE MAGNITUDE OF THE MEASURED ELECTRIC FIELD INDICATES THAT THE FILAMENT IS PROPERLY ORIENTED WITH RESPECT TO SAID REFERENCE POINT ON SAID BASE. 